Up to 50% of the impressions served on a static mobile banner ad are from accidental clicks or "fat finger" taps, according to GoldSpot Media's "Fat Finger Report."

Accidental clicks or "fat finger" clicks are taps on mobile banner ads that happen after less than two seconds of engagement. That is, if a user closes the app or website within two seconds of clicking the ad then it is considered accidental.

GoldSpot Media, a digital ad management platform for online and mobile advertising, aggregated this data by analyzing millions of static and rich media banner impressions for campaigns delivered in Q3 2012, which used the GoldSpot ad platform.

GoldSpot also found that "fat fingers" are three times more likely to accidentally tap static banner ads than they are to click rich media banners. This is because static banner ads "appear to be part of the content, and may be tapped by the user unintentionally." Whereas the 3D and animated qualities of Rich media are easier to differentiate from the app or website content.